There is a compelling need for prospective, properly controlled studies in women with epilepsy (WWE) during pregnancy to improve maternal and child outcomes. The proposed investigations are pertinent to the NINDS Epilepsy Research Benchmarks and will address multiple gaps in our knowledge noted by the recent American Academy of Neurology guidelines. This multicenter investigation will employ a prospective, observational, parallel-group, cohort design with an established research team. The specific aims are to: 1) Determine if WWE have increased seizures during pregnancy and delineate the contributing factors; 2) Determine if C-section rate is increased in WWE and delineate contributing factors; 3) Determine if WWE have an increased risk for depression during pregnancy and post-partum period and characterize risks factors; 4) Determine the long- term effects of in utero AED exposure on verbal intellectual abilities and other neurobehavioral outcomes in the children of WWE; 5) Determine if small for gestation age and other adverse neonatal outcomes are increased in children of WWE; 6) Determine if breastfeeding when taking AEDs impairs the child's verbal intellectual and other cognitive abilities. An overall goal f the proposed research is to establish the relationship between AED exposure and outcomes in the mother and child as well as describe and explain the variability in AED exposure and response. Anticonvulsant blood levels (ABLs) and area-under-the- concentration-time-curves (AUCs) will be used as direct measures of drug exposure. The results will enable clinicians to prospectively calculate individual dosing regimens for the mother in order to optimize dosing and limit unnecessary drug exposure to the child. In addition, genetic samples will be collected, which will provide a valuable resource for future pharmacogenetics studies to further delineate individual variability across patients.